Comparison of Somatic and
Autonomic Systems
Divisions of the ANS
• ANS divisions:
–
• mobilizes the body during _
–
• performs
___________________________________________
and conserves body energy
• The two divisions provide _
Role of the Parasympathetic Division
• Concerned with keeping body energy use low
• Involves the _
–
• Its activity is illustrated in a person who relaxes after
a meal
•
– Blood pressure, heart rate, and respiratory rates are low
– Gastrointestinal tract activity is high
– The skin is warm and the pupils are constricted
Role of the Sympathetic Division
• The sympathetic division is the _
• Involves _
– exercise, excitement, emergency, and
embarrassment
Role of the Sympathetic Division
• Promotes adjustments during exercise
– blood flow to organs is reduced, _
• Its activity is illustrated by a person who is
threatened
– Heart rate ______________________________ and
breathing is _
– The skin is cold and sweaty, and the pupils dilate
Anatomy of ANS
Division
Location of
Ganglia
Origin of Fibers
Length of Fibers
Sympathetic
Thoracolumbar
region of the spinal
cord
Short preganglionic
and long
postganglionic
Close to the
spinal cord
Parasympathetic
Brain and sacral
spinal cord
Long preganglionic
and short
postganglionic
In the visceral
effector organs
Parasympathetic Division Outflow
Cranial Outflow
Sacral Outflow
Cranial Nerve
Ganglion
Effector Organ(s)
Occulomotor (III)
Ciliary
Eye
Facial (VII)
Pterygopalatin
Submandibular
Salivary, nasal, and
lacrimal glands
Glossopharyngeal
(IX)
Otic
Parotid salivary glands
Vagus (X)
Located within the
walls of target organs
Heart, lungs, and most
visceral organs
S2-S4
Located within the
walls of the target
organs
Large intestine, urinary
bladder, ureters, and
reproductive organs
Sympathetic Outflow
• Arises from spinal cord segments T1 through L2
• Sympathetic neurons form _
• Preganglionic fibers pass through the
______________________________________
and synapse in the chain (paravertebral)
ganglia
Sympathetic Outflow
• Fibers from T5-L2
– form _
– synapse with _
• Postganglionic fibers innervate the numerous
organs of the body
Sympathetic Trunks and Pathways
• The __________________________________
form part of the sympathetic trunk or chain
• Typically there are 23 ganglia
– 3 cervical
– 11 thoracic
– 4 lumbar
– 4 sacral
– 1 coccygeal
Sympathetic Trunks and Pathways
Figure 14.6
Sympathetic Trunks and Pathways
•
A preganglionic fiber follows one of three
pathways upon entering the paravertebral
ganglia
1. Synapse with the _
2. _______________________________________
the sympathetic chain to synapse in another
chain ganglion
3. Pass through the chain ganglion and _
Pathways with Synapses in Chain
Ganglia
• Postganglionic axons enter the ventral rami via
the _
• These fibers innervate _
• Rami communicantes are associated
_______________ with the sympathetic
division
Pathways to the Head
• Preganglionic fibers emerge from T1-T4 and
synapse in the superior cervical ganglion
• These fibers:
– Serve the _
– Stimulate dilator muscles of the _
– Inhibit nasal and salivary glands
Pathways to the Thorax
• Preganglionic fibers emerge from T1-T6 and
synapse in the _
• Postganglionic fibers emerge from the middle
and inferior cervical ganglia and enter nerves
C4-C8
• These fibers innervate the
___________________ via the cardiac plexus,
as well as innervating the _
Pathways to the Thorax
• Other T1-T6 preganglionic fibers synapse in the
nearest chain ganglia
• Postganglionic fibers directly serve the
–
–
–
–
Pathways with Synapses in Collateral
Ganglia
• These fibers (T5-L2) leave the sympathetic
chain _
• They form thoracic, lumbar, and sacral _
• Their ganglia include
– the
– the superior and inferior mesenterics
– the
Pathways to the Abdomen
• Sympathetic nerves innervating the abdomen
have preganglionic fibers from T5-L2
• They travel through the thoracic splanchnic
nerves and synapse at the celiac and superior
mesenteric ganglia
• Postganglionic fibers serve the
Pathways to the Pelvis
• Preganglionic fibers originate from T10-L2
• Most travel via the
_____________________________________
splanchnic nerves to the inferior mesenteric and
hypogastric ganglia
• Postganglionic fibers serve the distal half of the
large intestine, the
____________________________________, and
the reproductive organs
Pathways with Synapses in the Adrenal
Medulla
• Fibers of the thoracic splanchnic nerve pass _
• Upon stimulation, medullary cells secrete
______________________________________
______________________________________
into the blood
Visceral Reflexes
• ____________________________reflexes
have the same elements as
_______________________________reflexes
• They are always _
• Afferent fibers are found in spinal and
autonomic nerves
Referred Pain
• Pain stimuli arising
from the
__________________
are _
• This may be due to
the fact that visceral
pain afferents travel
along the same
pathways as somatic
pain fibers
Neurotransmitters and Receptors
• Acetylcholine (ACh) and norepinephrine (NE) are the two
major neurotransmitters of the _
•
– ACh-releasing fibers
– ACh is released by all
__________________________________________ axons and
all parasympathetic _
• Adrenergic fibers
– ______________________________________________
postganglionic axons that release NE
• effects (excitatory/inhibitory) _